The Classroom / Path 3 · Bitcoin
What is Bitcoin?
Money that nobody can print more of. This path compares two ways of creating money, shows the schedule you can check for yourself, and takes the strongest case against Bitcoin seriously.
The question
Two ways to create money
One kind of money grows whenever its managers decide. The other follows a schedule anyone can check. What is Bitcoin, and why does that limit matter?
M2: Federal Reserve via FRED (M2SL), seasonally adjusted, nominal dollars. Bitcoin: Bitcoin white paper and protocol rules; mined supply about 20.08 million as of September 2026 (Clark Moody Dashboard).
The idea
Bitcoin, in plain English
Three or four sentences in my own words. The core idea: Bitcoin is money that runs on a public ledger thousands of computers keep together, with no bank or government in the middle, and a supply limit nobody can change on their own.
Words for this step: Bitcoin Blockchain Mining Halving Node
Follow one payment
01 · Wallet: Construct + sign
Your wallet doesn't hold little digital coins. It finds the bitcoin you're allowed to spend and uses your private key to sign this one payment. The signature proves you approved it without revealing the key.
02 · Transaction: Spending instructions
The payment points back to bitcoin you received before and writes new instructions: one part to your friend, any leftover back to you as change. The gap between what goes in and what comes out is the fee for the miner.
03 · Nodes: Check + relay
Your wallet sends it out to computers running Bitcoin. Each node checks for itself: does the signature work, do the coins exist, were they already spent? Pass, and it waits in the mempool and gets passed on. Fail, and it's rejected, no matter who sent it.
04 · Miner: Propose + prove work
Miners gather valid payments into a candidate block and race to find a result below the network's target: a lottery where every ticket costs real work (proof of work). The winner broadcasts the block. It's still only a proposal.
05 · Block: Nodes check again
Nodes check the block for themselves. Invalid, and it's thrown out, however much electricity it took. Valid, and it joins the blockchain: your payment has its first confirmation. Every block built on top makes it harder and more expensive to reverse.
Miners propose. Nodes verify. At no point does one bank, company, miner or developer get to declare a payment valid by authority alone.
From Bitcoin 101, ep. 5, “How Bitcoin Works.” Based on Satoshi Nakamoto, “Bitcoin: A Peer-to-Peer Electronic Cash System” (2008), sections 2–5. Icons as used in the lesson slides.
The evidence · don't trust, verify
The schedule anyone can check
The other side · challenge the idea
Isn't it just speculation?
The strongest case against Bitcoin, taken seriously. Pick the one that matters most: wild price drops, the energy it uses, or “it has no cash flow, so it's only worth what the next buyer pays.” What it gets right, where I disagree, and what would change my mind.
Check yourself
Could you explain it to a friend?
A third question about the other side, once step 4 is written.